Variable geometry centrifugal pump



2 Sheets-Sheet l B. SAMERDYKE VARIABLE GEOMETRY CENTRIFUGAL PUMP Oct.29, 196s Filed April 14, 1967 NME,

ATTORNEY OCR 29, 1968 B. P. SAMERDYKE VARBLE GEVOMETRY CENTRIFUGAL PUMP2 Sheets-Sheet 2 Filed April 14, 1967 United States Patent O 3,407,740VARIABLE GEOMETRY CENTRIFUGAL PUMP Bertram P. Samerdyke, Lyndhurst,Ohio, assignor to Borg- Warner Corporation, Chicago, Ill., a corporationof Illinois Filed Apr. 14, 1967, Ser. No. 630,862 6 Claims. (Cl. 10S-97)ABSTRACT OF THE DISCLOSURE A variable capacity centrifugal pump whichincludes a two-section impeller and which is axially adjustable to varythe pump flow rate. The diameter across the impeller vanes convergestoward the axis of rotation, and the vanes are masked to present variouseffective impeller diameters at various adjusted positions. Axialmovement of one member results in adjustment of both the effectivecrosssectional flow area and the effective impeller diameter.

Summary of the invention The present invention relates generally tovariable capacity centrifugal pumps and more particularly to such pumpswhich are adjustable to vary their operational characteristics.

Heretofore variable capacity pumps have been provided in which sectionsof the impeller have been axially adjustable for varying the flow rateof the pump while maintaining a constant impeller diameter. The vanes ofprior impellers impart identical velocity components to the fluid alongthe axial extent of the vane outer edge. Inasmuch as the pressure of thefluid is dependent in part upon the velocity imparted to it by theimpeller vane, at least a portion of the pressure generatingcapabilities of the pump remained invariable. Variation of capacity wasobtained by varying the effective cross-section flow area of the fluidpassage through the pump.

It is an object of the present invention to extend the operating rangeof variable capacity pumps by providing additional pressure variationsthrough an impeller having a variable effective diameter. Such variableeffective diameter can be advantageously provided by vanes havingoblique outer or peripheral edges. One factor influencing the variablepressure capabilities is the difference in velocity of differentincremental portions of the vane outer edge. For a given rotationalimpeller speed, different increments of the vane edge rotate atdifferent linear velocities because of their different radial spacingfrom the axis of rotation. A further factor influencing the variablepressure characteristic is the direction of the velocity components ofthe fluid leaving the edge of the impeller vane. Where the edge of thevane is oblique, and the vane is offset from the axis of rotation, eachincrement of the edge has a slightly different angular relationship withrespect to a plane extending along the impeller axis, resulting in adifferent direction for the fluid velocity components generated by thatparticular edge increment. Thus the fluid velocities generated along theoblique edge of the vane, differ in :both magnitude and direction, andmasking selected portions of the `edge provides a means for varying thepressure performance characteristics of the pump.

Brief description of the drawings In the drawings:

FIGURE l is a longitudinal section view taken -along the axis of a pumpaccording to the present invention;

FIGURE 2 is a View similar to FIGURE l showing portions of the impellerassembly in adjusted position for varying the performancecharacteristics of the pump;

FIGURE 3 is a view taken `along the line 3--3 of FIG- URE 2 withportions of the impeller base section broken away to more clearly revealthe vane section of the impeller assembly; and

FIGURE 4 is a view similar to FIGURE 3 showing a modification ofimpeller vane construction.

FIGURES 5 and 6 are fragmentary plan views illustrating slightlymodified forms of the invention.

FIGURE 7 is a fragmentary plan view illustrating still another modifiedform of the invention.

Description of the preferred embodiments Referring now to the drawingsand more particularly FIGURE 1 thereof, the reference character 10generally indicates a portion of a variable capacity centrifugal pumpaccording to the present invention including a casing 11 and an impeller12.

Casing 11 is formed of front and rear body units 13 and 14 secured toeach other in endwise assembly by cap screws 16. Front body unit 13 isprovided with a mounting flange 17 for connection to a fluid source.Extending axially inwardly from flange 17, internally of body unit 13,is a throat i9 providing an inlet for pump 10.

Front body unit 13 is provided Iwith. a wear ring 21 adjacent throat 19which may advantageously be composed of a graphitic compositionproviding both a bearing and a fluid seal around portions of impellerassembly 12. A web portion 22 extends annularly about throat portion 19terminating in a stepped flange 23. A groove 24 in stepped flange 23provides a seat for VO-ring seal 26. Stepped flange 23 is secured tomating ange 27 of rear body unit 14.

Rear :body unit 14 is radially enlarged adjacent flange 27 to provide ascroll-like configuration 29 within the casing, including outlet port28. A second weblike portion 31 extends between scroll portion 29 and anaxially extending tubular portion 32 of rear body unit 14 rotatablysupporting an end of impeller assembly 12.

Inipeller assembly 12 includes a base section 42, and a vane section 45arranged for relative axial movement with respect to each other to varythe size of the fluid passage extending between inlet throat 19 and theoutlet port 28. The fluid passage extending through the pump is dened inpart by the front face 63 of base section 42 and the annular web 64 ofvane section 45. Varying the sizeof the flow passage as defined by face63 and annular web 64 provides a means for varying the capacity or flowrate of the pump.

The hollow drive member 34 include-s splines 36 carried on an innersurface thereof engagea-ble with mating splines 37 of shaft 38. Drivemember 34 includes collar portion 39 adjacent a journal portion 41, bothof which engage sleeve bearing 33 for concentrically and axiallyaligning impeller assembly 12 with respect to pump casing 11 Thedisklike impeller base section 42 is bored and counterbored at 43 and 44for assembly with journal portion 41 of drive member 34 and may besecured thereto by screws 18. Base section 42 is provided with aplurality of grooves 62 extending inwardly from the front face 63thereof, and may, if desired, extend entirely therethrough in the mannerof slots. Journal portion 41 of drive means 34 is counterbored at 46 andprovided with a key seat 47 therein. A shaft 48 is axially slideable inbore 46 guided by key 49 engaged with keyways 47 and S1. The rearwardend of shaft 48 is provided with screw threads 52 and a nut 53 bearingagainst collar 54. Compression spring 56 is fitted between collar 54 andrecess 57 in journal portion 41 of drive member 34, biasing shaft 48 inan axially rearward direction. Shaft 38 includes an aperture 58 throughwhich pressure fluid can be admitted to bear on nut 53 and the exposedend of shaft 48 for adjustin-g the axial position thereof against thebias of spring 56.

Vane section 45 of impeller assembly 12 includes a plurality of vanes 61extending outwardly from a hublike spinner 59 located on the forward endof shaft 48. Both vane section 45 and base section 42 are rotatablydriven by drive member 34 which in turn is driven by shaft 38. Therearwardmost portions 67 of vanes 61 extend into the grooves or slots 62such that disk-like base member 42 masks a portion of the axial lengththereof. The forward portion 68 of vanes 61 merge into the annular web64 surrounding a tubular hub portion 66 in alignment with throat 19 ofcasing 11. Tubular hub portion 66, annular web 64 and vanes 61 togetherwith the shaft 48, form vane section 45 of impeller assembly 12. Therearmost portion 67 of vanes 61 are provided with an inner steppedportion 60 arranged to clear the bottom portion of grooves or slots 62.

The outer edges 69 of vanes 61 are oblique with respect to the face 63of Abase section 42, adjacent axial increments thereof varying in radiusfrom the axis of rotation of the impeller assembly. As shown moreclearly in FIGURE 3, vanes 61 may be of planar configuration parallelwith but offset from the axis of rotation of the impeller assembly. Inthe construction shown in FIGURE 3, oblique vane edges 69 are orientedin a conical configuration, the axis of which is on the axis of rotationof impeller assembly 12.

Vanes 161, shown in FIGURE 4, are of nonplanar configuration, however,the outer edges 169 thereof are also oriented in a conicalconfiguration.

Further inspection of FIGURE 3 reveals some of the unobvious features ofthe oblique edge configuration 69. For example, adjacent increments ofoblique edge 69 are circumferentially and radially displaced from eachother. Thus adjacent incremental portions of edge 69 travel at slightlydifferent velocities lin slightly different directions thereby impartingdifferent vector velocities to the portions of fluid in contacttherewith. For example, a portion of fluid contacting vane 61 at thelocation 71 has an outward velocity component W1 parallel to the planarvane 61 at the angle B1 with respect to linear velocity component U1,resulting in a fiuid velocity V1 at the angle a1. For purposes ofcomparison, a distant increment at location 72 is also illustrated.Another portion of iiuid in contact with vane 61 at location 72 has anoutward velocity component W2 parallel to planer vane 61 but at adifferent angle B2 with respect to the linear velocity U2. It should beobserved that the linear velocity components U1 and U2 are not parallelto each other and are of different magnitudes even though they aregenerated by the same planar vane 61. Where the vanes 161 are ofnonplanar configuration the magnitudes and directions of the variousvelocity components, as illustrated at locations 171, 172 and signifiedby primed reference characters, show an even greater difference.

As described above, each incremental portion of the oblique edge 69 or169 imparts a different velocity to the fluid in contact therewith, thecumulative effect being approximately equal to the median value betweenthe extremes. Where portions of vane 61 and 161 are masked within thegrooves or slots of base section 42, the corresponding incremental edgeportions are removed from effective contact with the fluid, theremaining edge portions deter-mining the velocity imparted to the fluid.Thus as illustrated in FIGURES 1 and 2, vanes 61 have an effective ormedian diameter D1 midway between the vane outer extremity and the pointof intersection with the face of base member 42. As illustrated inFIGURE 2, the vanes have a different effective diameter D2 which issmaller than D1 when the impeller sections 42, 45 are moved apart toincrease the sizeof the liow passage.

Inasmuch as the pressure imparted to the fluid is proportional to thevelocity with which it leaves the impeller, it is believed evident thatthe impeller vanes of the present 4 invention, having converging edgeswhich can be masked to provide different effective diameters, arecapable of providing a wider range of operating pressures than ispossible with pumps having a fixed impeller diameter. The wider range ofoperating pressures provided by the variable diameter impeller, togetherwith the variable flow rate provided by axial adjustment of the impellersections, thus provide a variable capacity pump having an extendedoperating range in terms of pressure-volume capacity.

Referring now to FIGURES 5 and 6, there are shown slightly modifiedforms of impeller vane construction.

In FIGURE 5 vanes 261 are provided which include outer oblique edges 269which converge in a direction toward a base 242 but not linearly. Theedge shape is convex as viewed from the exterior of the pump housing.With this construction movement of one of the separate impeller sectionswith respect to the other produces an alteration of the effectiveimpeller diameter in a manner similar to that of the arrangement ofFIGURES 1 through 4. However, the rate of change of effective diameteriu relation to the change in axial height of the impeller outlet isslightly varied as compared to the corresponding rate of changeobtainable with the construction of f' FIGURES 1 to 4.

FIGURE 6 illustrates an impeller having vanes 361 which include outeredges 369 which are convex as viewed from the exterior of the pump.Again a non-linear change in effective impeller diameter is produced bythis arrangement.

Referring now to FIGURE 7 there is shown a still further modification ofthe invention. An impeller 412 is provided which includes a base section442 and a vane section 445. The vane section includes a plurality ofvanes 461 having oblique outer edges 469 similar to those of theimpeller of the embodiment shown in FIGURES l through 4, However, thebase section 442 does not include grooves such as the grooves 62 shownin FIGURE 1, but rather includes a plurality of masking fins 85 whichcooperate with the vanes of the impeller vane section. As in theprevious described embodiments one of the separate impeller sections ismovable with respect to the other and movement of that section iseffective to change the effective impeller diameter to provide thedesired variation in performance characteristics.

Having shown and described a preferred embodiment of the inventiontogether with a modified form thereof, it is understood that variousother modifications and variations of the construction shown, areincluded within the spirit of the invention and scope of the followingclaims.

I claim:

1. A variable geometry centrifugal pump including a casing having aninlet and an outlet and a rotatable impeller mounted within said casing,said impeller including a base section and a vane section, said basesection including vane receiving means, said vane section including aplurality of vanes having outer peripheral edges, at least a portion ofsaid outer peripheral edges being oblique to said base section havingadjacent increments thereof varying in radial disposition with respectto the axis of rotation of said impeller, said impeller section beingpositioned with said oblique outer peripheral edges disposed partiallywithin said vane receiving means of said base section at least partiallymasking said vane oblique outer edge portions to define an impellerdiameter at said base section, the remainder of said outer peripheraledges extending from said base section to define an effective pumpingdiameter of said impeller, one of said base section and vane sectionbeing movable with respect to the other thereof to vary the amount ofsaid oblique outer peripheral edges disposed within said vane receivingmeans thereby varying the impeller diameter at said base section and thelength of said oblique outer edges extending from said vane receivingmeans to vary the effective pumping diameter of said impeller.

2. The invention according to claim 1 in which said vane edge portionsextend circumferentially away from a plane through the axis of rotationof said impeller, adjacent axial increments of said vane edge portionvarying in circumferential displacement from said plane.

3. The invention according to claim 1 in which said vane edge portionsare disposed within a convergent surface of revolution generated aboutthe axis of revolution of said impeller.

4. The invention according to claim 1 in which said base and vanesections define a fluid passage extending between said casing inlet andOutlet, relative movement of said base and vane sections toward and fromeach other being etective to simultaneously vary the effective diameterof said impeller vanes while varying the size of said ow passage, saidsimultaneous variation of ow passage size and effective vane diameterproviding an extended operating range of pressure-volume characteristicsfor said pump.

5. The invention according to claim 1 in which said vane edge portionpresents a smaller radial dimension adjacent the intersection of saidbase section and vane section, said base and vane sections coasting witheach other to simultaneously increase the effective diameter of saidimpeller While restricting said flow passage.

References Cited UNITED STATES PATENTS 2,927,536 3/1960 Rhoades l 103-972,992,617 7/1961 Kroeger 103-115 3,116,396 1/1964 Deters 103-102 FOREIGNPATENTS 24,402 12/ 1929 Australia. 41,436 7/ 1937 Netherlands.

HENRY F. RADUAZO, Primary Examiner.

LAURENCE V. EFNER, Examiner.

